How GPS Works in Wearables (and Why It Kills Your Battery)

                     How GPS Works in Wearables (and Why It Kills Your Battery)
               



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                     How GPS Works in Wearables (and Why It Kills Your Battery)
               
Categoria: Tutoriais | FreeCodeCamp Premium
Idioma Principal: Português (Conteúdo de Tecnologia)

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A couple of months ago, I went for a 10K run with three different devices on me. Why? Another long story of review deadlines and my own procrastination.

By the time I was done with my run and got back home, the smartwatch that was using GPS had close to 15% battery left. But the smart band and the smart ring which were using my phone's GPS stayed put.

That's when it clicked how much GPS actually costs a device and how little most people understand what's happening when their watch gives them directions on a new hiking trail.

So let's get into it: what GPS in a wearable device actually does, why it's such a battery hog, and how to save on battery during long hikes.

Table of Contents

• What's Actually Happening When Your Watch Says "Acquiring GPS"

• GPS, GLONASS, Galileo, and Why Your Watch Uses All of Them

• Why This Eats Battery Like Nothing Else

• Standalone GPS vs Phone-Connected GPS

• Which Wearables Actually Hold Up (and Which Ones Don't)

• What Wearable Brands Are Doing to Fix This

• How to Save Battery Without Losing Your GPS Data

• The Trade-Off Isn't Going Away Anytime Soon

What's Actually Happening When Your Watch Says "Acquiring GPS"

Your wearable isn't just listening to the signal of one satellite. It listens to the signals of at least four satellites orbiting the Earth, then calculates the location based on how long it took for each signal to reach the watch.

This technique is called trilateration, and the basic math principles are the same for your smartphone, your car's navigation system, and your watch.

This isn't an easy task since there's a tiny antenna in your watch and a tiny processor performing calculations in real-time. Not just one calculation, thought: it's performed every second while the device is on and while you're moving. This means that every second or so your watch gets and calculates the signal of satellites that are literally more than 12,000 miles away from the Earth.

That's a lot to do for such a small device.

GPS, GLONASS, Galileo, and Why Your Watch Uses All of Them

Modern wearables rarely use GPS alone anymore. They draw on the signals provided by GPS (US-based), GLONASS (Russia), Galileo (Europe), as well as QZSS or BeiDou in some cases, depending on the chip set.

By drawing on the signals from more than one satellite system at a time, your wearable will be able to get and maintain the signal more quickly and more accurately, particularly when there's less sky visibility, like in a dense urban environment or while moving under a tree canopy.

It's a very practical feature. I've tested wearables that required minutes to get a GPS signal, as well as a later model from the same brand, equipped with multi-band capability, that connected almost instantly.

The downside to drawing on several different satellite systems is that it requires more radio activity and so uses up more battery. It's a trade-off between accuracy and speed and battery life, which not many users understand.

Why This Eats Battery Like Nothing Else

It's safe to say that GPS functionality is one of the biggest battery hogs out there. And here's what makes it such an energy-sucking machine.

First of all, the GPS radio is active during your entire workout or activity. In contrast to a heart rate monitor that takes samples several times per second and only syncs with the app when the app is open, a GPS chip won't rest while it's worki

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